The invention relates to a method for determining a wear value for a transmission element, in particular, a timing chain or a toothed belt, arranged between a crankshaft and a camshaft of a reciprocating piston internal combustion engine, wherein the camshaft is driven by the transmission element via a drive part, such as, e.g., a camshaft gearwheel. In addition, the invention relates to a reciprocating piston internal combustion engine with a crankshaft, at least one camshaft, and at least one transmission element connecting these to each other, in particular, a timing chain or a toothed belt, wherein the transmission element is in driving connection with the camshaft via a drive part, such as, e.g., a camshaft gearwheel.
Such a reciprocating piston internal combustion engine with a crankshaft and two camshafts controlling intake and exhaust valves is known in practice. On the crankshaft there is a crankshaft gearwheel, which is locked in rotation with the crankshaft and which drives a timing chain. A camshaft gearwheel, which is locked in rotation with the relevant camshaft, is allocated to each camshaft and features twice the diameter of the crankshaft gearwheel. The timing chain engages with external teeth of the camshaft gearwheels and in this way transmits the rotational movement of the crankshaft to the camshafts with a rotational speed ratio of 2:1. At high rotational speeds, relatively large tensile forces occur, because the timing chain drives not only the camshaft allocated to it, but instead also the valves and valve springs activated by the camshaft. Increased running output of the internal combustion engine leads to wear, especially at the individual bearing points of the chain elements of the timing chain. Therefore, the length of the timing chain increases and the phase position of the camshaft relative to the crankshaft is changed, which has an unfavorable effect on the operating behavior of the internal combustion engine and results in an increase in fuel consumption and/or a decrease in the engine output. The state of the timing chain is therefore checked regularly, in order to replace the timing chain, if necessary, when a predetermined wear limit is reached. The checking of the timing chain, however, is relatively complicated, because parts of a control box of the reciprocating piston internal combustion engine and possibly other components, such as, e.g., an air filter, a generator, an engine cover, or the like, must be removed, in order to obtain access to the timing chain. The wear of the timing chain is determined by measuring the distance between the tensioned section and the loose section and/or by determining the position of a tensioning element of an adjustable chain tensioner when the internal combustion engine is stopped. For a precise check of the wear on the timing chain, it is even necessary to disassemble the timing chain. It is also disadvantageous that the intervals, within which the timing chain must be checked, must be designed for the most unfavorable operating conditions of the internal combustion engine, so that even under the most unfavorable operating conditions, the reaching of the wear limit of the timing chain can be recognized in due time and the timing chain can be replaced.